1. Field of the Invention
The present invention relates to a hydraulic system provided on a vehicle, and more particularly to a hydraulic system to be used for transmitting power to a working machine, for instance, in an agricultural tractor or the like.
2. Description of the Prior Art
In the heretofore known agricultural tractor or the like, it was a common practice that normally an engine is loaded on a front portion of a vehicle body and a transmission casing is disposed on a rear portion of the vehicle body, thereby wheels were driven by the engine through a transmission system in the transmission casing, and besides the above-mentioned drive system, there was provided a hydraulic system which employed an oil pump driven by the engine as a hydraulic pressure feed source, and a working machine was driven by this hydraulic system. The hydraulic system consists of the above-mentioned oil pump, a control valve and a hydraulic cylinder, delivered oil from the oil pump is controlled by the control valve and fed to the hydraulic cylinder, and the working machine is driven by the intermediary of a piston of the hydraulic cylinder so that the working machine can be, for example, elevated or lowered.
In such a hydraulic system, heretofore the oil pump was mounted to the engine and was directly coupled thereto. On the other hand, the control valve was disposed on the rear portion of the vehicle body remote from the engine for convenience in manipulation, and accordingly, the oil pump and the control valve had to be connected with each other through a relatively long high-pressure piping.
Moreover, since the oil pump would vibrate jointly with the engine, it was necessary to form the above-mentioned high-pressure piping as a flexible piping.